Bug#819100: linux-image-4.4.0-1-amd64: Mute and Mic-Mute LEDs no longer work on Thinkpad T410

[Alex Goebel]

In 3.19, the way the kernel handles that button was changed from 
hardware to software. You'll need

options thinkpad_acpi software_mute=0
in modprobe.d/ to get the old behaviour back.

-Alex